T. Marshall Hahn Jr., who as president of Virginia Tech transformed it from a regional military college with a mostly white, mostly male student body into a diverse, internationally renowned research university, died on May 29 at his home outside Blacksburg, Va. He was 89.

The university, in Blacksburg, announced the death.

In 1998, in a retrospective examination of Dr. Hahn’s career, The Roanoke Times called him “the man who made Tech what it is today.”

A physicist by training, Dr. Hahn assumed the presidency of Virginia Polytechnic Institute, as it was then known, in 1962. At the time, enrollment numbered not much more than 6,000.

Although students at the institute’s associated women’s college, Radford College (now Radford University), could attend courses at Virginia Polytechnic, the student body was nominally all male. And though the institute had admitted its first black student in 1953, it remained overwhelmingly white.

Founded in 1872 as Virginia Agricultural and Mechanical College, Virginia Polytechnic had maintained a vigorous military tradition from its inception. At the time Dr. Hahn took office, participation in the college’s Corps of Cadets remained mandatory for all students. But that requirement, he realized, had discouraged many prospective applicants.

In his more than 12 years as president, Dr. Hahn created 30 new undergraduate majors, among them art, history, philosophy, sociology, psychology and management; added some 20 graduate programs; and established the colleges of arts and sciences, architecture and education.

He also oversaw the construction of more than two dozen campus buildings.

In 1970, the college was awarded full university status, becoming Virginia Polytechnic Institute and State University, its formal name to this day.

In a move that incensed many alumni donors, Dr. Hahn eliminated compulsory cadet service in 1964. That year he also severed ties with Radford College and began admitting women to the regular student body.

In 1965, aided by a $100,000 grant, Dr. Hahn established a scholarship program for enrollees of modest means, with most of the money earmarked for black students. The grant, from the Rockefeller Foundation, was believed to have been the first for this purpose awarded to a Southern land-grant college.

In an article about the award that year, The New York Times wrote, “Although it would seem to be a risky matter for a virtually all-white state college in the South to espouse a program that will bring in a sizable number of Negroes — ‘token’ integration is still the rule at many Southern institutions that must look to the state for support — Dr. Hahn declares that the venture was ‘extremely well received, almost surprisingly so,’ in the community.”

By the time Dr. Hahn left the presidency in 1974, Virginia Tech’s enrollment had nearly tripled, to 17,400. Today, its student body comprises roughly 17,000 men and 13,000 women. More than 1,100 students identify themselves as African-American, more than 1,500 as Hispanic and more than 2,500 as Asian.

The son of Thomas Marshall Hahn and the former Elizabeth Boston, Thomas Marshall Hahn Jr. was born on Dec. 2, 1926, in Lexington, Ky. A brilliant student, he parted company with his high school long before the traditional graduation age because, the school said, it had no more to teach him.

By the time he was 18, he had earned a bachelor’s degree in physics from the University of Kentucky. At 23, after two years’ naval service, he received a doctorate in the field from the Massachusetts Institute of Technology.

Dr. Hahn joined the Virginia Polytechnic physics faculty in 1954, becoming the department chairman. He left in 1959 to take a post as dean of arts and sciences at what is now Kansas State University, before returning in 1962 to become, at 35, Virginia Polytechnic’s 11th president.

After leaving the university in 1974, Dr. Hahn became an executive vice president of Georgia-Pacific, the paper company. He retired in 1993 as the company’s chief executive.

Dr. Hahn’s first wife, the former Margaret Louise Lee, known as Peggy, whom he married in 1948, died in 2009. His survivors include two daughters, Anne Hahn Hurst and Betty Hahn, and three grandchildren. His second marriage, to Jean Quible, ended in divorce; a son, William, from Dr. Hahn’s first marriage, died before him.

In an interview with The Roanoke Times in 1991, Dr. Hahn described taking the helm of Virginia Polytechnic and glimpsing the vast potential beneath its surface.

“I saw Virginia Tech as a sleeping giant that could be awakened,” he said. “I thought the time was right.”

A version of this article appears in print on , on Page A21 of the New York edition with the headline: T. M. Hahn, 89, Is Dead; Reimagined Virginia Tech. Order Reprints | Today’s Paper | Subscribe